LHM Hydraulic Fluid

[John Park]

Folks:

I happen to have a supply of LHM+ hydraulic fluid, as used in Rolls-Royce and Citroen cars.  It's a very light mineral oil, not the ordinary DOT4 glycol-based stuff - does anyone know any reason why it wouldn't be satisfactory as an after-run oil in our engines?

Regards
John

[Dave Hull]

I can't think of a specific reason not to try it, to see how you like it. If I had a bunch on hand with no other good use for it, I would.

There are a couple of things that you might consider:

1. It needs to have proper anti-corrosion additives if you are going to store the engines with this coating the insides. I think all the manufacturers would put this package in,  based on the types of metals used in the application it was designed for. For example, aluminum, steel, perhaps brass which is the likely issue in most cases. If it was sold for automotive applications, you can be pretty sure it isn't just plain mineral oil.

2. It shouldn't be overly prone to oxidizing, but again, they likely have anti-oxidizers added to it for a car application, which is good. But if it gets gummy, you won't like it.

3. I don't see it contaminating the glow plug, but since you don't know what all the additives might be, you'll have to test it and watch for that.

4. It shouldn't attack the plastic or rubber parts if they are synthetic materials. Like buna o-rings, Delrin venturi, etc.

5. There shouldn't be much of it inside when you try to start it the next time, so fuel compatibility wouldn't seem to be a serious issue. However, it reportedly is not considered miscible with methanol at ambient temperatures, so putting fuel thru the engine may not easily/quickly "wash it out."  If your oil is dyed (it would be dyed red if it was aviation oil) then you might put in a good amount on a test engine, and then try flooding your engine with model fuel to see if any dyed oil remains. I would look specifically at whether the model fuel "runs around" clumps of the mineral oil. If it does, that would be the end of testing for me.

Just a few thoughts. Let us know how you make out.

Dave

[John Park]

Dave:

Many thanks for this - I've always used ordinary light machine oil in the past, but will try the LHM+ and see how it performs.

Regards
John

[Dave Harmon]

Usually I avoid making any comments about after run oil because all sorts of stuff gets insisted upon and usually someone gets pissed.
But.....if the discussion goes on long enough.....usually I can't stand it and have to make some comment(s).

I have tried everything including Rislone recommended by GMA.
Rislone discolored the pot metal cases.....didn't do THAT again.

I'm not saying the usual after run oil didn't work....just that there was always some attribute that prevented me from continuous use.

What works for me is.....
Castor.....works but solidifies....naaaa
Refrigerant oil....works but too hard to get.....naaa
Marvel oil....works but stinks.....naaaa
Gun oil....works but stinks....naaaa
LPS....works but stinks....naaaaa
Kroil....works but stinks....naaaa
PB Blaster....this stuff stinks SO bad that the wife will pitch a tent for you in the back yard.
There are a few more I have tried but you get the idea.

What I finally settled on is......Castrol fully synthetic 00-20 motor "oil" available at Walmart.
It works great, available, does not solidify or get gummy, good long term storage oil, good after run oil, does not affect the glow plug because it is a lot like the synthetic oil we all use.....AND...it doesn't stink!!

Even though the engine may have a lot of this oil inside and flooding the plug, the engine starts right up without flushing it out first....it seems to be much like the synth oil used in glow fuel.
I don't think the weight of the Castrol makes much difference but I like to use the thinnest I can find.
I use it after every flying session and haven't had a rusted or corroded engine in years. 

Try it!   

[Phil Spillman]

Air Tool oil has worked for me for the past 20 years or so with no adverse consequences! Can be found at most hardware stores including Harbor Freight. Not expensive at all!

Phil Spillman

[John Park]

Hi, Everybody,

And thanks for all the input - it told me a lot I didn't know.  By the way - when it came to stinky lubricants, the ultimate must have been the tallow my father and his motorcycling mates used to use on their final drive chains, way back before I was born.  Solid at room temperature, it had to be heated on a stove and the chain immersed in it for about fifteen minutes, then removed and hung up to drain and cool.  The old man attempted to do this over the kitchen stove, but so vile was the stench that he was instantly banished to the far end of the garden with a Primus stove and strict instructions never to allow the stuff inside the house ever again - a story my mother just loved to tell whenever the said motorcycling mates were present!

Thanks again,
John

[bob whitney]

No  the ultimte was the fish oil that came in the front forks of the Japanese motoX bikes back in the 70's

[Dan McEntee]

No  the ultimte was the fish oil that came in the front forks of the Japanese motoX bikes back in the 70's

     YEAH!! After rebuilding a few sets of Hodaka front forks that have been setting around for 4 years, I have not smelled anything that can match that !!
   Type at you later,
   Dan McEntee

[John Park]

I should have said - according to my old man, the tallow he used wasn't the usual beef or mutton fat.  He claimed it was GOAT'S tallow!  (So it might just have run that Japanese fish oil a close second for pungency!)